Each main area of mathematics has its own top-level navigation page, which we refer to as the front page. If you go to the front page for a particular subject you will find links to articles and navigation pages that are particularly relevant to that subject. Not all front pages are for branches of mathematics as traditionally conceived: some are devoted to wide-ranging mathematical themes such as inequalities, modular arithmetic, or solving equations. See What kind of problem am I trying to solve? for a list of these.